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NOVEMBER 18, 1938 



I. Summary. 
II. Introduction. 
III. Formation and Organization of the Institute. 
IV. The Work of the Institute. 

A< Development and Performance of Air-Track. 

B. The Work of the Broadcasting Division, 

C. Other Developments of the Institute. 
V. Conclusion. 

VI . Bibliography. 


The Washington Institute of Technology wa3 formed in 1933 to de- 
velop an instrument landing system, already well begun at the Bureau of 
Standards. It has its offices located in Washington, D. C. and its experi- 
mental laboratory at College Park, Maryland. Closely associated with it and 
also located at College Park, Maryland is its two "manufacturing associates" 
Air- Track and Scientific Concrete Service Corporation. 

The Institute's chief objective is to test and develop more fully 
the present Air-Track equipment. The Air-Track instrument landing system em- 
ploys three elements, the runway localizer for guidance in the horizontal 
plane, the glide path for guidance in the vertical plane, and the marker bea- 
con to serve as a warning to the pilot of the proximity of the airport. All 
the ground equipment except the marker beacon is located in an automobile 
trailer which may be moved to other runways as weather conditions dictate. 
AIbo located in the trailer is an automatic monitoring device which insures 
the operation of the transmitters within closely prescribed limits. In the 
plane the pilot has a visual cross-pointer instrument on the instrument panel, 
which enables him to follow a curved path down to the runway and a safe land- 
ing in any kind of weather. 

The Broadcasting Division of the Institute renders valuable service 
to radio stations and radio engineers- This service includes allocation engi- 
neering, site surveys, coverage surveys, directional antennae design, construc- 
tion of antennae tuning and phasing equipment, and a frequency monitoring ser- 

In addition to these major interests, the Washington Institute of 
Technology holds the patent rights on many other devices which have been 


developed in connection with their regular work. 

Since its inception in 1933, the Institute has steadily grown in 
size, and with the probable adoption of an instrument landing system at all 
airports, it is safe to assume that it will enjoy a continued growth and 



The Washington Institute of Technology is a corporation which was 
formed for the purpose of experimentation and further development of an instru- 
ment landing system previously conceived by certain scientists at the Bureau 
of Standards. The progress accomplished at the Bureau of Standards ha3 teen 
adequately covered "by a previous thesis entitled "History and Development of 
the Bureau of Standards' Radio Beacon Experiment Station at College park, 
Maryland", written by Robert W. Beckham and dated December 18, 1936. It is 
the purpose of this thesis to set forth the history and development of the 
Washington Institute of Technology which is, in effect, an account of the sub- 
sequent developments along this line. It is for the instrument landing system, 
known as Air-Track, that the Institute has achieved an international renown. 

The offices of the Institute are located at present on the eighth 
floor of the McLachlen Building, 10th and G Streets, N.W. , Washington, D. C. 
The laboratory, where all the research and testing is done, is located at Col- 
lege Park, Maryland and is Just south of the College Park Airport in a conven- 
ient position for experimentation in airplane instrument landing systems. As- 
sociated with the laboratory is a factory for the manufacture of Air-Track 
equipment and also a laboratory for the purpose of research in the scientific 
control of concrete ingredients and strength. The last named establishments, 
however, do not belong to the Washington Institute of Technology proper, but 
are closely associated with it. 

Aside from the above permanent locations, there are field parties 
which are established in various localities as situations warrant. For ex- 
ample, at the present time a party is located in Pittsburgh because of the 
installation of Air-Track equipment at the Pittsburgh Airport. The Washington 
Institute of Technology is centered at College Park, Maryland with offices in 
Washington, D. C. 


As mentioned briefly above, the earlier developments of an airplane 
instrument landing system were first developed at the Bureau of Standards in 
Washington, D. C. However, the Economy Act, passed by Congress in 1933, made 
it necessary either to discharge the scientists connected with this work or to 
give them work in which they were not interested. It was at this time that 
Col. Sidney F. Mashbir organized the Washington Institute of Technology and in- 
vited the Bureau of Standards' scientists to join his organization and continue 
their research where it had been so abruptly terminated at the Bureau, 

Thus, the chief objective in forming such a company was for the pur- 
pose of research and further development of an instrument landing system. 
Since that time, the Institute has gained other aims, but still its predomi- 
nant work is in the testing and further development of Air-Track. 

The Washington Institute of Technology is incorporated in the State 
of Delaware and the controlling interest of stock is held by Col. Sidney F» 
Mashbir, who is the president of the company. At present the Institute is fi- 
nancially self-supporting due to its income for services rendered to radio sta- 
tions and radio engineers which will be e^ilained in more detail later. The 
Institute is subdivided into two main divisions, the Aircraft Radio Division 
and the Broadcasting Division, each of which has its distinct work to do, al- 
though they are very closely connected. 

The personnel of the Institute has steadily grown since its incep- 
tion in 1933. As mentioned above, the president is Col, Sidney F. Mashbir, 
while the nucleus of the company still comprises the scientists who have 
left the Bureau of Standards- The following men were all originally connected 


with the Bureau. Gomer L. Davies is the Chief of the Aircraft Eadio Division 
and Dr. Frank G. Kear ia the Chief of the Broadcasting Division. They were 
accompanied by engineers Gerald H. Ifintermute, now the senior engineer of the 
Aircraft Eadio Division, and the late William Or ton and also by the mechani- 
cians Hi chard Greene, senior mechanician, who is at present employed at Pitts- 
burgh, Harold Horsman, and Daniel %brand, Both of whom are employed at College 
Park, Maryland. From this small group in 1933 the Institute has grown until 
its staff now numbers over 20 engineers and technicians. 



The Air-Track instrument landing system is a proposed solution of 
the problem of landing a plane safely when the visibility is very poor. It 
consists essentially of three distinct transmitters — the runway localizer, 
the glide path, and the marker "beacons — each of which has its own function 
to perform. 

The runway localizer transmitter employs two loop directional an- 
tennae placed at an angle to each other. It depends for its success on the 
fact that a loop antennae sends out its maximum power in the plane of the 
loop and none at right angles to the loop. If points of equal field inten- 
sity be plotted, it is found that the radiation pattern is in the form of a 
figure eight. When two loop antennae are used in conjunction at an angle to 
each other, the points of similar field intensity from each loop overlap, 
giving four paths at right angles to each other along which the radiations 
from both loops are of equal intensity. One of these paths is directed down 
the runway and by his instruments the pilot can determine whether he is to the 
right or left of the runway, since the field intensity from one loop will be 
greater than that from the other loop if the pilot is off his course. Natural- 
ly, it will be necessary that the radiations from the two loops be different 
in form in order that it will be possible to distinguish between the two and 
thus determine in which direction the pilot is off the course. Formerly this 
was accomplished by use of the "interlocking A and K, signals." This merely 
means that the A ( * -~ ) is sent out on one loop, while the N ( — •) is sent 
out on the other. However the signals alternate. In other words, the dash 


Note Cross-Pointer Instrument 
above Instrument Panel 

Schematic Diagram Showing: 

(1) Boundary Marker Beacon 

(2) Control Room 

(3) Trailer in Position 


of the N would "be sent out on the first loop; followed by the dot of the A 
on the second loop; followed by the dot of the N on the first loop, and that 
in turn followed "by the dash of the A on the second loop, and then repeat the 
cycle. If the pilot was on his course, the signal he received in his phones 
was a steady Team, which would change to a condition where one signal predomi- 
nated if he strayed from his course. However, this system proved undesirable 
and has been replaced in Air-Track equipment by a modulation system, wherein 
the carrier wave has a frequency of 110 megacycles which is modulated to a 
frequency of 90 cycles in one loop and 150 cycles in the other loop. 

These impulses are separated in the plane hy means of a reed-conver- 
ter . This merely consists of two vitrating reeds, each of them having a na- 
tural vibrating frequency coinciding with the modulated frequency from one of 
the loops. The output from these reeds "buck" each other and actuate a verti- 
cal pointer which swings to the right or left as the field intensity changes. 
Thu3, when it is exactly vertical, the pilot is on his course. 

This runway localizer beam gives the pilot guidance in the horizon- 
tal plane so that he can head directly down the runway. However, he also needs 
guidance in the vertical plane so that he will land at the right point. This 
is the function of the glide path transmitter. The points of equal field in- 
tensity lie on a curve similar to the one shown in the accampanying figure* 
Of course an infinite number of such curves exist. This is utilized by tun- 
ing the receiver in the plane to the particular curve best adapted to the 
natural gliding angle of that plana. Also by varying the output of the trans- 
mitter these curves can be raised or lowered in order to clear obstacles or 
flying hazards. 


General Shape of Curve Joining Points of Equal Field Intensity 
Emitted by the Slide Path Transmitter 

The Pilot Follows the Lower Portion of the Curve 


Ordinarily there would tie similar curves emitted to the rear of the 
transmitter and away from the runway. However these are removed "by the use 
of reflectors thus leaving only the desired curves down the runway. 

The output from the receivers actuate a horizontal pointer which 
goes above or below its neutral position to correspond with the position of 
the plane above or below its predetermined path. This instrument is so con- 
structed that, if perchance the receiver or transmitter should cease to oper- 
ate, the pointer will fall below the horizontal, indicating to the pilot that 
he is below his path and he will climb, thus placing himself out of danger* 

By combining the runway localizer and the glide path, the pilot has 
guidance in both the horizontal and vertical planes. However, it i3 highly 
desirable that the pilot should know his approximate position, relative to the 
field* This is accomplished by placing a marker beacon at the approach end 
of the runway and also another at a known distance beyond the end of the run- 
way. As the pilot flies through the vertical "curtain" sent up by the marker 
beacons, be hears a tone in his phones and a light flashes on his instrument 
panel. This enables him to tell rhon he is over the field. Tho marker bea- 
con aerial is permanent in position and is strung close to the ground. Thu3 
it interferes in no way with the landing of the plane and is not a flying 

The frequency used on the runway localizer transmitter is 110 mega- 
cycles; that of the glide path transmitter is 91 megacycles, and the marker 
beacons operate on 75 megacycles. There was considerable difficulty encoun- 
tered in developing the present ultra-high frequency transmitter used for 
the localizer, however it is much superior to the original type, since it is 
not as readily affected by weather conditions. Also this system is unique 
in that all the ground equipment, except the marker beacon, is located in an 


The fiist installation for instrument landing 
of aircraft under regular airline operating 
conditions, has been completed at Pittsburgh 
for use by Pennsylvania Central Airlines. 
Photo shows Air -Track portable transmitting 
equipment stationed on west end of 5700 ft. 
runway of Pittsburgh's famous all -paved air- 
port; also alternate positions at ends of other 
runways — the action of glide path, localizer 
and marker beacons — and of cross-pointer 
instrument by which pilot lands. 

boundry of field; 
actuates horizon- 
tal needle. 

Marker beacon at edge of field informs 
pilot when he crosses boundary, by 
sound in earphones and light flashing 
on instrument panel 

Four course 
localizer, range 20 
miles, actuates ver- 
tical needle. One 
beam projected 
along center of 
runway. Pilot 
knows when right 
or left of course; 
obtains position 
anywhere within 
40 - mile circ 

Trailer can easily be disconnected, 
towed to another position, connected 
and transmitters placed in operation 
in a few minutes. 

Pictorial Diagram of Air-Track Equipment in Operation 
at the Pittsburgh Airport 


automobile trailer which may lie moved from one runway to another to correspond 
with the prevailing weather conditions. This makes a single installation serve 
any number of runways. An added safety device is the automatic monitoring sys- 
tem which is located in the trailer and consists essentially of a receiver 
which insures that the transmitters shall operate within closely prescribed 
limits. If not within these limits, the transmitters are shut off and a warn- 
ing signal is sent to the control tower at the airport, from which the proper 
adjustments are made. 

The equipment in the plane is very simple, consisting merely of a re- 
ceiver employing a detector circuit and two stages of audio amplification. It 
is very compact in form and all of the equipment, with the exception of the 
control box» can be located at any convenient place in the plane. Thus the 
only part of the equipment which must be in the pilot's cockpit is the control 
box and the visual cross-pointer instrument on the instrument panel. This use 
of the visual indicator instead of the older aural method marks a long step 
forward, inasmuch as it allows the pilot to maintain voice communication with 
the airport throughout the entire time interval of landing. 

The introduction and general use of such an instrument landing sys- 
tem should have a tremendous effect on airline development in the future. 
First and most important of all, it will promote safety especially in bad 
weather and decrease materially the number of accidents which occur at air- 
ports during the approach and landing operations. In addition, it will faci- 
litate traffic control at airports and make it possible to land more planes 
in the same amount of time, thus relieving congestion at the more crowded air- 
ports. Also it will make possible the establishment and maintenance of regu- 
lar airline schedules in spite of the weather. This will result in a tremen- 
dous increase in the number of passengers to travel by airplane, if they can 
depend on the printed schedule. 


Airplane Recently Acquired "by Air-Track 
for Experimental Purposes 


With so many obvious advantages in the use of such a system, it is 
logical to ask, "Why has it not been adopted and in general use?" There are 
many reasons for the delay. It is the general belief that its installation 
will have to come as a Federal aid to airports because of the cost. At pre- 
sent, the Bureau of Air Commerce has no authority to use its funds for air- 
port improvements but only for airway aids (between airports). Such authori- 
zation must come from Congress which introduces considerable question as to 
its probable time of. adoption. Furthermore, it will be necessary to first 
agree on a system which is acceptable to all concerned and then to train 
pilots in its use. All these details require time and must be further de- 
veloped before adoption. 


In addition to the work done by the Washington Institute of Tech- 
nology in the testing and development of Air- Track equipment, it also renders 
valuable service to radio stations and radio engineers. These services cover 
many fields and, while some are routine duties, others require much technical 
knowledge and foresight. All, however, are very necessary to commercial radio 

Under the head of allocation engineering are included all the de- 
tails and considerations which enter into the allotting of frequency bands to 
radio stations. This work is concerned mostly with the opening of new sta- 
tions and the insurance of their proper operation. Also in connection with 
this work, the Institute conducts site surveys. These surveys are made to 
determine the effect of buildings, ore deposits, etc. on transmitters, and to 
determine the most advantageous place at which to locate a permanent radio 


The Radio Laboratory of the Washington Institute of Technology 
at College Park, Maryland 


station. In order to do this, portable transmitters are set up at the place 
in question and the location tested. Such surveys eliminate the guess-work 
in the location of a station and prevent the construction of an expensive 
broadcasting station only to find that it is in a poor location. 

The Institute also conducts coverage surveys for radio stations al- 
ready in existence in order to determine the strength of the emanations from 
the station and the amount of territory which a radio station serves. This 
has an important commercial aspect since the station can base its charges to 
commercial advertisers on the number of people which it reaches. This is es- 
pecially important in metropolitan areas. 

In addition, the Institute also is doing important research work 
in the development of proper designs for directional antennae in order to 
prevent interference between radio stations. Furthermore, it develops and 
constructs all manner of antennae tuning and phasing equipment. This con- 
struction is done at College Park, Maryland and the equipment is sold to ra- 
dio stations and radio engineers. 

In addition to these services, the Institute conducts a frequency 
monitoring service consisting of routine tests on operating stations to de- 
termine their frequency accurately. The frequency of the station is calibra- 
ted against the signal received from the Bureau of Standards by telephone 
which is accurate to one cycle in ten million cycles over a period of one 
minute. By comparing the two signals and counting the number of beats, the 
number of cycles that the frequency being tested is in error may readily be 
determined. This is done periodically to insure that the station is within 
the limits prescribed by the Federal Communications Commission and is conduc- 
ted for the benefit of the radio station. This work is all done on a contract 
basis and helps materially to make the Institute financially self-supporting. 



Although the development of Air-Track and the services rendered to 
radio stations, as described above, constitute the major part of the work 
done "by the Washington Institute of Technology, there are several additional 
developments which are worthy of note. The Washington Institute of Technology 
holds patent rights on many important developments, largely in the realm of 
radio* These include several important innovations in the design of direction- 
al antennae. Also an improved radio direction finder has been developed large- 
ly in connection with its aeronautical experimentation. Another device known 
as the gun compass has also been perfected. This is a variation of the earth 
inductor compass and finds its chief application in small boats, since it is 
not so readily affected by the rocking motion. Another development consists 
of a low capacitance cable for use in ignition systems of airplanes or automo- 
biles, giving a hotter and larger spark. It has been used for several years 
in Naval aircraft. These developments are merely a few of the many patents 
held by the Washington Institute of Technology. 

There is one other organization which is closely allied with the 
Washington Institute of Technology and should be mentioned. It Is known as 
the Scientific Concrete Service Corporation. Its organization is entirely 
separate from the Washington Institute of Technology. However, actually, it 
is closely allied. It holds a position similar to Air- Track. Scientific Con- 
crete Service Corporation has developed a means of accurately controlling the 
ingredients of a mixture of concrete. By insuring a precision control of 
these ingredients, especially water, it is possible to effect a saving in ce- 
ment and also insure more uniform strength in the final concrete. The Cor- 
poration also has an establishment at College Park, Maryland. Thus at College 


Park, Maryland is located the Washington Institute of Technology laboratory 
and its two "manufacturing associates", Air- Track and Scientific Concrete 
Service Corporation. 



Until the present time, the Washington Institute of Technology has 
"been very successful in its developments and has steadily grown in size. It 
renders valuable aid to radio stations, and if instrument landing systems 
are installed in all airports, as they probably will be in the future, their 
services will be in demand because of their previous experience. If the sys- 
tem adopted is Air-Track, the Institute will grow much faster. In the light 
of the above observations, it is the opinion of the writer that the Washington 
Institute of Technology will continue to grow in the future, barring unfore- 
seen difficulties of a financial or technical nature. 

Before concluding, the writer would like to express his sincere 
thanks for the courteous aid which was extended to him by members of the Wash- 
ington Institute of Technology staff, and especially to Dr. Frank G. Kear, 
Chief of the Broadcasting Division, and Mr. Charles 1. Planck, who have been 
most obliging in extending the information needed for a thesis of this nature. 



"Report on the Status of Instrument Landing Systems" 

V f . 3. Jackson, Chief of Radio Development Section, 
Bureau of Air Commerce, Safety and Planning Division. 

"The Washington Institute of Technology Air- Track Jtystem of Instrument 

"by Hemy W, Roberts in "Aero Digest", April, 1937. 

"Under The Weather " 

"Fortune Magazine", June, 1938 

Air Commerce Bulletins 

#23, Volume I, Pages 5-6 
# 8, Volume I, Pages 15 - 16 
#20, Volume II, Page 526 

Bureau of Standards Research Papers No. 435 and Ho. 581 


Dr. Frank 5. Kear, Chief of the Broadcasting Division of the 

Washington Institute of Technology 
Mr. Charles S. Planck, Publicity Manager of the Washington 

Institute of Technology